Check valve



FIG. 1 is a perspective view of a first embodiment of a check valve;

FIG. 2 is a front view of the check valve of FIG. 1;

FIG. 3 is a rear view of the check valve of FIG. 1;

FIG. 4 is a right side view of the check valve of FIG. 1;

FIG. 5 is a left side view of the check valve of FIG. 1;

FIG. 6 is a top view of the check valve of FIG. 1;

FIG. 7 is a bottom view of the check valve of FIG. 1;

FIG. 8 is a perspective view of a second embodiment of a check valve;

FIG. 9 is a front view of the check valve of FIG. 8;

FIG. 10 is a rear view of the check valve of FIG. 8;

FIG. 11 is a right side view of the check valve of FIG. 8;

FIG. 12 is a left side view of the check valve of FIG. 8;

FIG. 13 is a top view of the check valve of FIG. 8; and,

FIG. 14 is a bottom view of the check valve of FIG. 8.

CLAIM The ornamental design for a check valve, as shown and described.